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Printed wiring board and method for fabricating the same

a technology of printed wiring and manufacturing methods, applied in the direction of resist details, printed circuit aspects, printed circuit manufacturing, etc., can solve the problem of not being able to stably control the high or low relationship of pad/immediate vicinity region in the actual processing process, and posed problems similar to those of nmsd typ

Inactive Publication Date: 2007-03-01
SHINKO ELECTRIC IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0035] It is an object of the invention to provide a printed wiring board for preventing a mounted solder ball from being deformed and preventing a pad before being mounted from being destructed by controlling the pad for mounting the solder ball as a connection terminal provided at a wiring pattern from becoming higher than an immediate vicinity region.
[0051] According to the invention, the pad is constituted by laminating the conductive layer for the wiring pattern, the lower layer plating layer and the upper layer plating layer, the immediate vicinity region surrounding the pad is constituted by laminating the conductive layer, the lower layer plating layer (and the upper layer plating layer) and the solder resist layer, the thickness of the upper layer plating layer is negligible and therefore, a difference of heights of the pad and the immediate vicinity region is determined only by a thickness of the solder resist layer and therefore, by controlling the thickness of the solder resist layer within an allowable tolerance, the height of the upper face of the pad can be controlled so as not to exceed the height of the upper face of the immediate vicinity region.

Problems solved by technology

Further, the variation is brought about when the processing is carried out by controlling to form the Ni plating layer and form the solder resist layer within allowable tolerances and therefore, it is in fact impossible to stably control the high or low relationship of pad / immediate vicinity region in an actual processing process.
Although the conventional art structure and method are concerned with a pad mode posing the problem by the high or low relationship between the pad and the immediate vicinity region separated therefrom, there is also a pad posing a similar problem by a difference of heights of a pad and an immediate vicinity region brought into contact therewith.
Also in the case of the SMD type, a problem similar to that of the NMSD type is posed.

Method used

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  • Printed wiring board and method for fabricating the same
  • Printed wiring board and method for fabricating the same
  • Printed wiring board and method for fabricating the same

Examples

Experimental program
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embodiment 1

[0064]FIG. 5 shows a printed wiring board including a pad of an NSMD type (Non Solder Mask Define Type) according to an embodiment of the invention.

[0065] As shown by FIG. 5A, a printed wiring board 50 of the invention is formed with the wiring pattern 14 including the conductive layer of Cu or the like on the insulating board 12 of resin or the like. The wiring pattern 14 includes the portion 14A for a pad for mounting a solder ball and an immediate vicinity wiring 14B separated therefrom.

[0066] The pad 20 for mounting the solder ball is formed by coating the Ni plating layer 16 as an lower layer plating layer and the Au plating layer 18 as an upper layer plating layer in this order on the surface of the portion 14A for the pad of the wiring pattern 14. This is shown in the drawing as ‘20:14A+16+18’ as a supplementary note.

[0067] An immediate vicinity region 34 separated from the pad 20 is formed by the immediate vicinity wiring 14B separated from the portion 14A for the pad of ...

embodiment 2

[0083] The printed wiring board 50 of the invention shown in FIG. 5A may be modified as shown by FIG. 7.

[0084] According to an illustrated printed wiring board 52, the Au plating layer 18 is formed not only at the pad 20 but also at the immediate vicinity region 34. The Au plating layer 18 is very thin and therefore, even when the Au plating layer 18 is formed as in the embodiment, an influence is not effected on the high or low relationship between the pad 20 and the immediate vicinity region 34. An advantage in this case resides in that Ni plating and Au plating need not to be carried out separately but can be carried out continuously and the steps are simplified as explained below. On the other hand, a drawback thereof resides in that an amount of plating Au is increased.

[0085] An explanation will be given of steps of fabricating the printed wiring board 52 of the invention of FIG. 7 in reference to FIG. 8.

[0086] First, as shown by FIG. 8A, the wiring pattern 14 (14A, 14B) is ...

embodiment 3

[0090] The printed wiring board 50 according to the invention shown in FIG. 5A may be modified as shown by FIG. 9.

[0091] According to an illustrated printed wiring board 54, the Ni plating layer 16 of the immediate vicinity region 34 is not extended over to a total of the immediate vicinity wiring 14B but is formed locally only at a vicinity of an end portion thereof proximate to the pad 20. After all, the Ni plating layer 16 is arranged at the immediate vicinity region 34 for preventing the high or low relationship between the pad 20 and the immediate vicinity region 34 from being influenced by the thickness of the Ni plating layer 16, for that purpose, even when the Ni plating layer 16 is arranged at the vicinity of the end portion of the immediate vicinity region 34 proximate to the pad 20, expected operation is achieved sufficiently. An advantage in this case resides in that an amount of plating Ni can be reduced. On the other hand, a drawback thereof resides in that steps of f...

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PUM

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Abstract

The invention is characterized in a printed wiring board having a wiring pattern including a pad for mounting a solder ball as a connection terminal, wherein the pad is constituted by laminating a conductive layer constituting the wiring pattern, a lower layer plating layer, and an upper layer plating layer in this order; an immediate vicinity region surrounding the pad is constituted by laminating the conductive layer, at least the lower layer plating layer in the lower layer plating layer and the higher layer plating layer, and a solder resist layer in the order; a thickness of the upper layer plating layer is a thickness negligible in comparison with respective thicknesses of the lower layer plating layer and the upper layer plating layer; and a height of an upper face of the pad does not exceed a height of an upper face of the immediate vicinity region.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a printed wiring board having a wiring pattern including a pad for mounting a solder ball as a connection terminal and its fabricating method. [0002] Generally, according to a wiring pattern of a wiring board used for a semiconductor package, a predetermined portion thereof is formed as a pad for mounting a solder ball as a connection terminal. According to the pad for mounting the solder ball, a surface of a conductive layer of Cu or the like constituting the wiring pattern is generally subjected to plating of Ni / Au plating or the like in order to promote a solder bonding property. [0003]FIG. 1A shows a sectional structure of a vicinity of a pad for mounting a solder ball of a printed wiring board of a conventional art. An illustrated printed wiring board 10 is formed with a wiring pattern 14 including a conductive layer of Cu or the like on an insulating board 12 of resin or the like. The wiring pattern 14 include...

Claims

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Application Information

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IPC IPC(8): H01L23/48
CPCH05K3/243H05K3/3452H05K3/3457H05K2201/0191H01L2224/13H05K2201/099H05K2203/0571H05K2203/1476H05K2201/0989H05K1/02
Inventor ARAI, KOJIKIKUCHI, TOMOFUMIMARUYAMA, ATSUSHIWAKABAYASHI, HIDEYUKI
Owner SHINKO ELECTRIC IND CO LTD